On 02/25/13 05:20, Vitezslav Cizek wrote: > Dropping the O_NONBLOCK flag to open() solves the issue.
Doing that would have bad effects elsewhere, as it would allow some denial of service attacks. > A different fix was introduced to tar - dropping the flag with fcntl() > after a subsequent read/write returns EAGAIN. OK, I pushed the following patch into the gzip master; can you please give it a try? Thanks. Won't you folks have similar problems with other GNU utilities? GNU 'touch', for example. Can you propose patches for all these? Just look for O_NONBLOCK in the source code. >From 14e047601b273b3a5d436a3f360d7c4b71c5ebe5 Mon Sep 17 00:00:00 2001 From: Paul Eggert <egg...@cs.ucla.edu> Date: Mon, 25 Feb 2013 11:24:14 -0800 Subject: [PATCH] gzip: port to DMF file systems * util.c (read_buffer): When reading a file with O_NONBLOCK, if the read fails with errno==EAGAIN, clear O_NONBLOCK and try again. Problem reported by Vitezslav Cizek in <http://lists.gnu.org/archive/html/bug-gzip/2013-02/msg00030.html>. --- util.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/util.c b/util.c index cfd4e6c..c4c7f70 100644 --- a/util.c +++ b/util.c @@ -132,16 +132,35 @@ int fill_inbuf(eof_ok) } /* Like the standard read function, except do not attempt to read more - than SSIZE_MAX bytes at a time. */ + than INT_MAX bytes at a time. */ int read_buffer (fd, buf, cnt) int fd; voidp buf; unsigned int cnt; { + int len; if (INT_MAX < cnt) cnt = INT_MAX; - return read (fd, buf, cnt); + len = read (fd, buf, cnt); + +#if defined F_SETFL && O_NONBLOCK && defined EAGAIN + /* Input files are opened O_NONBLOCK for security reasons. On some + file systems this can cause read to fail with errno == EAGAIN. */ + if (len < 0 && errno == EAGAIN) + { + int flags = fcntl (fd, F_GETFL); + if (0 <= flags) + { + if (! (flags & O_NONBLOCK)) + errno = EAGAIN; + else if (fcntl (fd, F_SETFL, flags & ~O_NONBLOCK) != -1) + len = read (fd, buf, cnt); + } + } +#endif + + return len; } /* Likewise for 'write'. */ -- 1.7.11.7
